| Purine （C5H4N4） is a kind of alkaloids, an important component of nucleic acids. There arethree sources of purine, including nucleic acid catabolism, in vivo synthesis and food intake.Uric acid is the end product of purine degradation in human body, finally excreted from thekidney. Long-term intake of purine-rich foods such as meat and seafood, coupled with someinducing factors, can easily lead to the deposition of uric acid, which can cause hyperuricemiaor gout. For these diseases, in addition to medical treatment, the intake of purine from foodshould also be limited.Up to now in food composition table, there is no accurate data about purine content. Thereported values in the literatures vary greatly. Some literatures suggest that purines aremetabolized differently and produce different uricogenic effects in animals and humans.Therefore, to develop an accurate, simple and reliable method for the determination of purinecompounds in meat is significant. To determine the amount of purine in different meat, toanalysis the purine content and proportion of different visceral organs, and to study thedistribution of purine in boiled meat and the soup are very helpful for people’s healthy diet, alsohave important public health significance for the prevention of hyperuricemia and goutoccurrence.Methods:1. Sample preparation: Purine nucleotide in meat was hydrolyzed into free bases withperchloric acid. After a series of processing, the solution was injected into HPLC system. Andthe perchloric acid concentration and hydrolysis time were optimized.2. HPLC analysis: The HPLC condition such as mobile phase, column, column temperature,flow rate and wavelength were optimized. An analytical method （HPLC） was developed todeterminate the purine compounds in meat.3. The purine content of fresh meat bought from the market was determinated; thedifferences of purine content and proportion of different visceral organs of new sacrificedanimals were analyzed; the meat was boiled with distilled water and sampled at 15, 30, 45,60min, using the proposed method to determinate the purine content in boiled meat and the soup.Results:1. The optimum conditions were as follows: The meat was hydrolyzed with perchloric acid10% （v/v） in boiling water for 60min. The hydrolysate were separated on an Agilent ZORBAXEclipse XDB-C18 column （250 mm×4.6 mm i.d., 5μm） at 25℃with a mobile phase of7.0×10-3mol/L KH2PO4-H3PO4（pH 4.0）, a flow rate of 1.0 mL/min, and UV detection at 254 nm. Under optimized conditions, each component in the corresponding concentration range showed agood linear relation with its peak area, correlation coefficient r>0.9999, recovery was 90.0%～107.5%, RSD was 1.7%～13.3%.2. The total purine content of the meat from low to high （100.3～221.3 mg/100g） was asfollows: beef, grass carp, pork, carp, mutton, rabbit, san-huang chicken, duck, prawn. In additionto containing four kinds of purines, there was quite amount of uric acid （8.3～20.1 mg/100g） inthe mentioned meat. The proportion of uric acid to total purine and uric acid was about 7%.3. The purine content of different visceral organs was determinated. The highest was liver,the second was kidney, followed by meat, heart and gizzards. The order of meat, heart andgizzards was different in different species. In meat, heart and gizzards, the content ofhypoxanthine respectively accounted for 70%, 45% and 35% of the total purine. While in liverand kidney, guanine and adenine respectively accounted for 50% and 35%.4. The purine content of meat decreased gradually during the boiling processes, mainly dueto the decrease of hypoxanthine. At last purine content accounted for 20%～30% of the freshmeat. The purine content in soup increased sharply during 15min, accounting for about 60%～70%, higher than boiled meat.Conclusion:The proposed method is simple, rapid, accurate and reliable for the determination of purinecompounds in meat. In addition to containing four kinds of purines, there is quite amount of uricacid in the mentioned meat. The proportion of uric acid to total purine and uric acid is about 7%.It is suggest that, except for purine, the content of uric acid in meat should be taken into accountfor gouty patients. The total content and proportion of purine are different in different visceralorgans. It is unreasonable that assessing the uricogenic potential of food and guiding the goutydiet only according to the total purine content. Boil can greatly reduced purine content in themeat, about 70%～80% of purine can release into the soup. Gouty patients can enjoy appropriateamount of boiled meat to supplement protein. |
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